A freezing and cracking resistant agent for ballastless track concrete and a preparation method and application thereof

Abstract

The application discloses a kind of freeze-proof anti-cracking agent for ballastless track concrete and its preparation method and application, belong to concrete admixture technical field, the preparation method of the freeze-proof anti-cracking agent for ballastless track concrete includes the following steps: after polyphenol compound dimer is modified, with amino acid in aqueous solution Schiff base reaction is carried out, then the obtained Schiff base reaction product, polyester compound, catalyst A is dissolved in solvent, acylation reaction is carried out under nitrogen environment stirring, after reaction is finished, aftertreatment is carried out, the freeze-proof anti-cracking agent is obtained.The product can effectively prevent the cracking of ballastless track concrete, has good anti-cracking effect.And, the freeze-proof anti-cracking agent for ballastless track concrete provided by the application does not add heavy metal raw materials in preparation process, with environmental friendliness, and preparation method is simple, easy to popularize and apply.

Description

Technical Field

[0001] This invention belongs to the field of concrete admixture technology, and particularly relates to an antifreeze and crack-resistant agent for ballastless track concrete, its preparation method and application. Background Technology

[0002] Due to its unique advantages, cast-in-place ballastless concrete track has been widely used in high-speed railways, heavy-haul railways, and urban rail transit. Ballastless track technology is a track technology that involves casting the track bed concrete in one step. This process is characterized by its ease of operation, safety, practicality, precise track geometry, and rapid positioning. Antifreeze and crack-resistant agents for ballastless track concrete play a crucial role in ensuring the stability and durability of the track structure. They not only significantly improve the frost resistance of concrete but also effectively prevent cracks from forming in low-temperature environments, thereby improving the durability and service life of the concrete. In low-temperature environments, concrete is easily damaged by the expansion force generated by the freezing of water. The active components in the antifreeze and crack-resistant agent can react with the water in the concrete to form a micro-bubble structure, effectively mitigating the pressure and stress caused by water penetration and expansion during freeze-thaw cycles, thus improving the frost resistance of the concrete. Furthermore, during the hardening process, concrete is prone to shrinkage and cracking due to changes in temperature and humidity. The antifreeze and crack-resistant agent can refine the cement particles in the concrete, promote the cement hydration reaction, and make the microstructure of the concrete denser, thereby reducing the formation of cracks. Antifreeze and crack-resistant agents can significantly improve the durability and service life of concrete by enhancing its freeze-thaw resistance and preventing crack formation, thereby reducing maintenance and replacement costs.

[0003] However, existing concrete antifreeze and crack-resistant agents still face key challenges. For example, they are typically expensive, increasing project costs. Furthermore, the use of some agents can negatively impact other concrete properties, such as reducing strength, workability, or delaying setting time. In addition, some agents contain chemicals and heavy metals, which, if not properly handled, could pollute the environment. With increasing environmental awareness, the environmental performance requirements for antifreeze and crack-resistant agents are becoming increasingly stringent.

[0004] Therefore, how to provide an environmentally friendly, compatible concrete antifreeze and anti-cracking agent with good antifreeze and anti-cracking properties is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes an antifreeze and crack-resistant agent for ballastless track concrete.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An antifreeze and crack-resistant agent for ballastless track concrete, with the following molecular structure:

[0008]

[0009] Wherein, R1 is -OH or H;

[0010] R2 is

[0011] R3 is

[0012] The m and n are positive integers, representing the number of repeating units in each part of the polymer. The range of m is 5-20, and the range of n is 500-2000.

[0013] A method for preparing an antifreeze and crack-resistant agent for ballastless track concrete includes the following steps:

[0014] After modification, the polyphenolic compound dimer is reacted with amino acids in an aqueous solution to form a Schiff base. The resulting Schiff base reaction product, polyester compound, and catalyst A are then dissolved in a solvent and stirred under nitrogen atmosphere to carry out an acylation reaction. After the reaction is completed, post-treatment is performed to obtain the antifreeze and anti-cracking agent.

[0015] Beneficial effects: Gallic acid, salicylic acid, and other polyphenolic compounds with high water retention capacity are chemical substances found in plants, possessing antioxidant, anti-inflammatory, and other biological activities. In the field of materials science, polyphenolic compounds have attracted much attention due to their water retention and ability to reduce material shrinkage. The phenolic hydroxyl groups in their structure allow them to effectively interact with water molecules to form hydrogen bonds, thus exhibiting good water retention, reducing drying shrinkage and crack formation, and possessing strong crack resistance.

[0016] Polyester compounds have relatively flexible molecular chain structures and long alkane chains. These alkane chains can absorb external stress through movement and slippage, thereby reducing crack formation. There are interactions between polyester molecules, such as hydrogen bonds and van der Waals forces, which can effectively transfer stress, preventing the material from cracking rapidly under stress and thus improving crack resistance.

[0017] This invention uses amino acids as antifreeze proteins, which prevent ice formation and growth by interacting with the surface of ice crystals. The resulting microcrystals can inhibit the propagation of matrix cracks. Furthermore, they can generate specific interactions with water molecules or the ice surface, thereby lowering the ice formation temperature, delaying the ice crystallization process, and enabling stable interactions with water or ice, thus achieving the antifreeze principle.

[0018] Preferably, the method for modifying polyphenolic compound dimers includes the following steps:

[0019] Add catalyst B to an aqueous solution of a polyphenol compound and react it at 50-70°C in an oxygen environment for 4-8 hours to obtain a polyphenol compound dimer solution. Mix the polyphenol compound dimer solution, thionyl chloride and catalyst C, and react it under nitrogen conditions for 6-10 hours. Then, after distillation and drying, the modified polyphenol compound dimer is obtained.

[0020] Preferably, the polyphenolic compound includes gallic acid or salicylic acid; and / or

[0021] The catalyst B comprises potassium permanganate or manganese dioxide; and / or

[0022] The catalyst C comprises N,N-dimethylformamide and / or dimethyl sulfoxide.

[0023] Preferably, the mass ratio of the polyphenolic compound to catalyst B is 1:(0.04-0.08); and / or

[0024] The mass ratio of the polyphenolic compound dimer to catalyst C is 1:(0.01-0.03).

[0025] Beneficial effects: Polyphenolic compounds have excellent water retention capacity, antioxidant properties and degradability. The large number of phenolic hydroxyl structures on their molecules can firmly lock in the water in the concrete system, reduce water evaporation, and exhibit excellent water retention. They can also reduce the drying shrinkage of concrete materials. At the same time, they can also act as modifiers to adjust the microstructure of hydration products, thereby improving the crack resistance and service performance of the concrete matrix.

[0026] Preferably, the Schiff base reaction specifically includes the following steps:

[0027] The pH of the aqueous solution of the modified polyphenolic compound dimer was adjusted to 7-9, and then an aqueous solution of amino acids was added dropwise while stirring under oxygen conditions. After the addition was completed, the reaction was stirred for 2-4 hours. Then the pH was adjusted to 5-7 to obtain the Schiff base reaction product.

[0028] Preferably, the amino acids in the aqueous amino acid solution include glutamic acid or aspartic acid.

[0029] The molar ratio of the amino acid to the modified polyphenolic compound dimer is (2-3):1.

[0030] Preferably, the polyester compound includes polybutylene succinate or polylactic acid; and / or

[0031] Catalyst A includes pyridine or dimethyl sulfoxide.

[0032] Beneficial effects: The antifreeze and crack-resistant agent in this invention, through the special structure of polyester and other components in its macromolecules, can significantly improve the toughness and fatigue resistance of cement-based materials, and reduce their brittleness. This performance improvement can effectively resist external cyclic loads and environmental influences, thereby extending the service life of ballastless tracks.

[0033] Preferably, the mass ratio of the polyester compound to the polyphenol compound dimer is (2-4):1; and / or

[0034] The mass ratio of catalyst A and solvent to polyphenolic compound dimer is (0.02-0.05):(2-4):1.

[0035] Preferably, the acylation reaction is carried out at a temperature of 30-40°C for 6-12 hours.

[0036] Preferably, the post-treatment involves cooling to room temperature, continuing stirring for 1-3 hours, followed by distillation, washing, and vacuum drying.

[0037] Application of an antifreeze and crack-resistant agent for ballastless track concrete in concrete.

[0038] A type of ballastless track concrete includes the aforementioned antifreeze and crack-resistant agent for ballastless track concrete; the amount of the antifreeze and crack-resistant agent added to the ballastless track concrete is 0.8-1% of the cementitious material.

[0039] Preferably, the cementitious material is cement, and more preferably, ordinary Portland cement.

[0040] More preferably, the concrete comprises the following components: substance A, substance B, sand, and crushed stone;

[0041] Substance A includes polycarboxylate superplasticizer, air-entraining agent, cementing material, and water;

[0042] The content of the polycarboxylate superplasticizer is 2-4% of the mass of the cementitious material, the content of the air-entraining agent is 0.4-0.8% of the mass of the cementitious material, and the amount of water added is 20-30% of the total mass of the cementitious material (cementing material and other cementing materials).

[0043] Substance B is other cementing materials, the above-mentioned antifreeze and anti-cracking agent for ballastless track concrete, and water;

[0044] The other cementing material is fly ash;

[0045] The content of the antifreeze and anti-cracking agent for the ballastless track concrete is 0.8-1% of the mass of the cementitious material, and the amount of water added is 10-15% of the mass of the total cementitious material (cementing material and other cementing materials).

[0046] Compared with the prior art, the present invention has the following advantages and technical effects:

[0047] This invention provides an antifreeze and crack-resistant agent for ballastless track concrete, its preparation method and application. The antifreeze and crack-resistant agent can effectively improve the low-temperature operation stability of ballastless track concrete, prevent cracking of ballastless track concrete, and has good antifreeze and crack-resistant effects.

[0048] This invention uses amino acids, polyphenolic compounds, and polyesters as raw materials. Most of these components are derived from renewable resources, resulting in a low environmental impact and classifying them as green and low-carbon materials. Compared to traditional antifreeze and anti-cracking agents (such as those containing chloride salts and other chemical components), the preparation process and application of this invention are environmentally friendly, contributing to sustainable development and reducing carbon emissions.

[0049] This invention introduces polyester compounds and amino acids as raw materials, resulting in an antifreeze and crack-resistant agent that exhibits significantly superior antifreeze performance compared to existing products in low-temperature environments. Specifically, the flexible chain structure of the polyester compounds and the hydrogen bonding and microcrystal-forming abilities of the amino acids effectively enhance the antifreeze and crack-resistant properties of cement-based materials, reducing the risk of cracking in ballastless track concrete under severe cold conditions.

[0050] In engineering applications, the use of polyester compounds, amino acids, and natural polyphenols as raw materials allows the antifreeze and crack-resistant agent prepared by this invention to reduce the use of chemical additives in production and application. The preparation process is simple and efficient, and it features low toxicity and high safety. Furthermore, the good compatibility and processability of these components broaden the application range of this antifreeze and crack-resistant agent and facilitate industrial production. This invention utilizes the interdisciplinary approach of antifreeze proteins (amino acids) from the biological field with building materials and polymer materials, demonstrating strong innovation. It can extend the service life of ballastless track concrete, significantly improve engineering quality, and reduce production costs, possessing enormous market potential and application value. Attached Figure Description

[0051] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0052] Figure 1 Figures showing the mass loss of ballastless track concrete after 100 freeze-thaw cycles obtained in Examples 1-4 and the comparative example;

[0053] Figure 2 The graph shows the strength loss of ballastless track concrete after 100 freeze-thaw cycles obtained in Examples 1-4 and the comparative example. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] This invention discloses a method for preparing an antifreeze and crack-resistant agent for ballastless track concrete, comprising the following steps:

[0056] (1) Preparation of polyphenolic compound dimers: Prepare an aqueous solution of polyphenolic compound with a mass concentration of 20-30%, adjust the pH of the solution to 7-10, adjust the temperature to 50-70℃, continuously stir and introduce oxygen during the reaction, add a catalyst, react at a constant temperature for 4-8 hours, cool to room temperature, and obtain a polyphenolic compound dimer solution.

[0057] (2) Preparation of modified polyphenol dimers: The polyphenol dimer solution obtained in step (1), thionyl chloride (SOCl2) and catalyst are added to the reactor. During the reaction, the mixture is continuously stirred and protected with nitrogen gas. The reaction is carried out for 6-10 hours, then distilled and dried to obtain modified polyphenol dimers.

[0058] (3) Schiff base reaction: The modified polyphenol dimer obtained in step (2) is prepared into an aqueous solution with a mass concentration of 20-30% and added to the reactor. The pH of the solution is adjusted to 7-9. Under room temperature conditions, the mixture is continuously stirred and oxygen is introduced. An antifreeze amino acid aqueous solution with a mass concentration of 20-30% is added dropwise for 4-8 hours while stirring. After the addition is completed, the reaction is stirred for 2-4 hours. After the reaction is completed, the pH is adjusted to 5-7 to obtain the Schiff base reaction product.

[0059] (4) Acylation reaction: The Schiff base reaction product obtained in step (3), polyester compound, catalyst and solvent are added to the reactor. During the reaction, the mixture is continuously stirred and nitrogen is introduced. The temperature is adjusted to 30-40℃ and the reaction is carried out at a constant temperature for 6-12 hours. After the reaction is completed, the mixture is cooled to room temperature and stirred for 1-3 hours. The mixture is then distilled, washed, and vacuum dried at 80-100℃ to obtain the antifreeze and crack-resistant agent for ballastless track concrete.

[0060] In some preferred embodiments, the polyphenolic compound in step (1) is gallic acid or salicylic acid; the catalyst in step (1) is potassium permanganate or manganese dioxide, and the mass ratio of the amount used to the polyphenolic compound in step (1) is 0.04-0.08:1.

[0061] In some preferred embodiments, the mass ratio of thionyl chloride used in step (2) to the solute in the polyphenolic compound dimer solution in step (1) is 2-3:1; the catalyst in step (2) is N,N-dimethylformamide and / or dimethyl sulfoxide, and the mass ratio of its amount to the solute in the polyphenolic compound dimer solution in step (1) is 0.01-0.03:1.

[0062] In some preferred embodiments, the antifreeze amino acid in step (3) is glutamic acid or aspartic acid, and the molar ratio of the solute in its aqueous solution to the modified polyphenol dimer in step (2) is 2-3:1.

[0063] In some preferred embodiments, the polyester compound in step (4) is polybutylene succinate or polylactic acid, and the mass ratio of its amount to the solute in the polyphenolic compound dimer solution in step (1) is 2-4:1; the catalyst in step (4) is pyridine or dimethyl sulfoxide, and the mass ratio of its amount to the solute in the polyphenolic compound dimer solution in step (1) is 0.02-0.05:1; the solvent in step (4) is dichloromethane or N,N-dimethylformamide, and the mass ratio of its amount to the solute in the polyphenolic compound dimer solution in step (1) is 2-4:1.

[0064] In some preferred embodiments, the molecular structural formula of the ballastless track concrete antifreeze and anti-cracking agent described in step (4) is as follows:

[0065]

[0066] R1 is -OH or H; R2 is R3 is

[0067] Where m and n are positive integers, representing the number of repeating units in each part of the polymer, with m ranging from 5 to 20 and n ranging from 500 to 2000.

[0068] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0069] Unless otherwise specified, room temperature or normal temperature in the embodiments of the present invention refers to 25±3℃.

[0070] Unless otherwise specified, all raw materials used in the embodiments of this invention were purchased through commercial channels.

[0071] Example 1

[0072] A method for preparing an antifreeze and crack-resistant agent for ballastless track concrete includes the following steps:

[0073] (1) First, 170.1g of gallic acid and 396.9g of water were prepared into a 30% mass concentration solution and added to the reactor. A 40% mass concentration sodium hydroxide aqueous solution was added to adjust the pH to 9. While stirring, the temperature was raised to 60℃. Oxygen was continuously introduced during the reaction. 6.8g of potassium permanganate was added and the reaction was stirred at a constant temperature for 4 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain a polyphenol compound dimer solution, and the mass concentration was adjusted to 30%.

[0074] (2) Add 283.3g of the polyphenolic compound dimer solution (mass concentration of 30%) obtained in step (1), 170g of thionyl chloride, and 1.7g of N,N-dimethylformamide to the reactor. Nitrogen gas is continuously introduced during the reaction. The reaction is carried out at a constant temperature and stirred for 8 hours. The mixture is then distilled and dried to obtain the modified polyphenolic compound dimer.

[0075] (3) Prepare a 30% solution by mixing 102.3g (0.5mol) of the modified polyphenol compound dimer obtained in step (2) with 238.7g of water and add it to the reactor. Then add a 30% sodium hydroxide aqueous solution and adjust the pH to 8. Continuously introduce oxygen at room temperature. Add a 20% glutamic acid solution prepared by mixing 73.6g of glutamic acid and 294.4g of water dropwise to the reactor for 4 hours. After the dropwise addition is completed, stir the reaction at a constant temperature for 2 hours. Then add a 2% hydrochloric acid solution and adjust the pH to 5 to obtain the Schiff base reaction product.

[0076] (4) The Schiff base reaction product obtained in step (3), 262g of polybutylene succinate (molecular weight 40000), 2.1g of pyridine and 204.6g of dichloromethane were added to the reactor, nitrogen gas was continuously introduced, and the reaction was carried out at a constant temperature of 30°C for 6h. After the reaction was completed, the mixture was cooled to room temperature and stirred for 2h. Then, it was distilled, washed and vacuum dried at 80°C to obtain the antifreeze and anti-cracking agent for ballastless track concrete.

[0077] A method for preparing ballastless track concrete includes the following steps:

[0078] (1) 5.9g of polycarboxylate superplasticizer (commercially available), 1.4g of air-entraining agent (commercially available), and 110g of water were mixed with 280g of cement (ordinary silicate cement P·O42.5) to obtain substance A;

[0079] (2) 2.25g of the antifreeze and crack-resistant agent for ballastless track concrete obtained in Example 1 and 66g of water were mixed with 160g of fly ash to obtain substance B;

[0080] (3) Mix material A, material B, 870g of sand (medium sand), and 784g of crushed stone (320g of 5-10mm crushed stone and 464g of 10-16mm crushed stone) evenly to obtain frost-resistant and crack-resistant modified ballastless track concrete.

[0081] Example 2

[0082] A method for preparing an antifreeze and crack-resistant agent for ballastless track concrete includes the following steps:

[0083] (1) First, 113.4g of gallic acid and 453.6g of water were prepared into a 20% mass concentration solution and added to the reactor. A 40% mass concentration sodium hydroxide aqueous solution was added to adjust the pH to 8. While stirring, the temperature was raised to 70℃. Oxygen was continuously introduced during the reaction. 9.8g of manganese dioxide was added and the reaction was stirred at a constant temperature for 6 hours. After the reaction was completed, it was cooled to room temperature to obtain a polyphenol compound dimer solution, and the mass concentration was adjusted to 30%.

[0084] (2) Add 283.3g of the polyphenolic compound dimer solution (mass concentration of 30%) obtained in step (1), 255g of thionyl chloride, and 0.85g of dimethyl sulfoxide to the reactor. Nitrogen gas is continuously introduced during the reaction. The reaction is carried out at a constant temperature and stirred for 6 hours. The mixture is then distilled and dried to obtain the modified polyphenolic compound dimer.

[0085] (3) Prepare a 20% solution by mixing 68.2g (0.5mol) of the modified polyphenol compound dimer obtained in step (2) with 272.8g of water and add it to the reactor. Then add a 30% sodium hydroxide aqueous solution and adjust the pH to 8. Continuously introduce oxygen at room temperature. Add a 20% aspartic acid solution prepared by mixing 73.6g of aspartic acid and 294.4g of water dropwise to the reactor for 6 hours. After the dropwise addition is completed, stir the reaction at a constant temperature for 3 hours. Then add a 2% hydrochloric acid solution and adjust the pH to 5 to obtain the Schiff base reaction product.

[0086] (4) The Schiff base reaction product obtained in step (3), 171g of polybutylene succinate (molecular weight 30000), 3.4g of pyridine and 331.5g of dichloromethane were added to the reactor, nitrogen gas was continuously introduced, and the reaction was carried out at a constant temperature of 35°C for 12h. After the reaction was completed, the mixture was cooled to room temperature and stirred for 1.5h. Then, it was distilled, washed and dried under vacuum at 100°C to obtain the antifreeze and crack-resistant agent for ballastless track concrete.

[0087] A method for preparing ballastless track concrete includes the following steps:

[0088] (1) 10.3g of polycarboxylate superplasticizer (commercially available), 1.1g of air-entraining agent (commercially available), and 110g of water were mixed with 280g of cement (ordinary Portland cement P·O42.5) to obtain substance A;

[0089] (2) 2.4g of the antifreeze and crack-resistant agent for ballastless track concrete obtained in Example 1 and 44g of water were mixed with 160g of fly ash to obtain substance B;

[0090] (3) Mix material A, material B, 870g of sand (medium sand), and 784g of crushed stone (320g of 5-10mm crushed stone and 464g of 10-16mm crushed stone) evenly to obtain frost-resistant and crack-resistant modified ballastless track concrete.

[0091] Example 3

[0092] A method for preparing an antifreeze and crack-resistant agent for ballastless track concrete includes the following steps:

[0093] (1) First, 141.75g ​​of gallic acid and 425.25g of water were prepared into a 25% mass concentration solution and added to the reactor. A 40% mass concentration sodium hydroxide aqueous solution was added to adjust the pH to 9. While stirring, the temperature was raised to 60℃. Oxygen was continuously introduced during the reaction. 8.5g of potassium permanganate was added and the reaction was stirred at a constant temperature for 4 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain a polyphenol compound dimer solution, and the mass concentration was adjusted to 30%.

[0094] (2) Add 283.3g of the polyphenolic compound dimer solution (mass concentration of 30%) obtained in step (1), 212.5g of thionyl chloride, and 2.1g of N,N-dimethylformamide to the reactor. Nitrogen gas is continuously introduced during the reaction. The reaction is carried out at a constant temperature and stirred for 8 hours. The mixture is then distilled and dried to obtain the modified polyphenolic compound dimer.

[0095] (3) Prepare a 30% solution by mixing 102.3g (0.5mol) of the modified polyphenol compound dimer obtained in step (2) with 238.7g of water and add it to the reactor. Then add a 30% sodium hydroxide aqueous solution and adjust the pH to 8. Continuously introduce oxygen at room temperature. Add a 20% glutamic acid solution prepared by mixing 73.6g of glutamic acid and 294.4g of water dropwise to the reactor for 8 hours. After the dropwise addition is completed, stir the reaction at a constant temperature for 4 hours. Then add a 2% hydrochloric acid solution and adjust the pH to 6 to obtain the Schiff base reaction product.

[0096] (4) The Schiff base reaction product obtained in step (3), 172.9g of polybutylene succinate (molecular weight 50000), 3.91g of pyridine, and 267.75g of dichloromethane were added to the reactor. Nitrogen gas was continuously introduced and the reaction was carried out at a constant temperature of 30°C for 10h. After the reaction was completed, the mixture was cooled to room temperature and stirred for 1h. Then, it was distilled, washed, and vacuum dried at 90°C to obtain the antifreeze and crack-resistant agent for ballastless track concrete.

[0097] A method for preparing ballastless track concrete includes the following steps:

[0098] (1) 11.2g of polycarboxylate superplasticizer (commercially available), 2.1g of air-entraining agent (commercially available), and 132g of water were mixed with 280g of cement (ordinary Portland cement P·O42.5) to obtain substance A;

[0099] (2) 2.8g of the antifreeze and crack-resistant agent for ballastless track concrete obtained in Example 1 and 55g of water were mixed with 160g of fly ash to obtain substance B;

[0100] (3) Mix material A, material B, 870g of sand (medium sand), and 784g of crushed stone (320g of 5-10mm crushed stone and 464g of 10-16mm crushed stone) evenly to obtain frost-resistant and crack-resistant modified ballastless track concrete.

[0101] Example 4

[0102] A method for preparing an antifreeze and crack-resistant agent for ballastless track concrete includes the following steps:

[0103] (1) First, 170.1g of gallic acid and 396.9g of water were prepared into a 30% mass concentration solution and added to the reactor. A 40% mass concentration sodium hydroxide aqueous solution was added to adjust the pH to 9. While stirring, the temperature was raised to 60℃. Oxygen was continuously introduced during the reaction. 6.8g of potassium permanganate was added and the reaction was stirred at a constant temperature for 4 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain a polyphenol compound dimer solution, and the mass concentration was adjusted to 30%.

[0104] (2) Add 283.3g of the polyphenolic compound dimer solution (mass concentration of 30%) obtained in step (1), 255g of thionyl chloride, and 2.5g of N,N-dimethylformamide to the reactor. Nitrogen gas is continuously introduced during the reaction. The reaction is carried out at a constant temperature and stirred for 8 hours. The mixture is then distilled and dried to obtain the modified polyphenolic compound dimer.

[0105] (3) Prepare a 25% solution by mixing 85.25g (0.5mol) of the modified polyphenol compound dimer obtained in step (2) with 255.75g of water and add it to the reactor. Then add a 30% sodium hydroxide aqueous solution and adjust the pH to 8. Continuously introduce oxygen at room temperature. Add a 20% glutamic acid solution prepared by mixing 73.6g of glutamic acid and 294.4g of water dropwise to the reactor for 5 hours. After the addition is completed, stir the reaction at a constant temperature for 2.5 hours. Then add a 2% hydrochloric acid solution and adjust the pH to 7 to obtain the Schiff base reaction product.

[0106] (4) The Schiff base reaction product obtained in step (3), 328.5g of polybutylene succinate (molecular weight 40000), 1.8g of pyridine and 188.4g of dichloromethane were added to the reactor, nitrogen gas was continuously introduced, and the reaction was carried out at a constant temperature of 40°C for 8 hours. After the reaction was completed, the mixture was cooled to room temperature and stirred for 3 hours. Then, it was distilled, washed and vacuum dried at 85°C to obtain the antifreeze and anti-cracking agent for ballastless track concrete.

[0107] A method for preparing ballastless track concrete includes the following steps:

[0108] (1) 8.4g of polycarboxylate superplasticizer (commercially available), 2.24g of air-entraining agent (commercially available), and 88g of water were mixed with 280g of cement (ordinary Portland cement P·O42.5) to obtain substance A;

[0109] (2) 2.6g of the antifreeze and crack-resistant agent for ballastless track concrete obtained in Example 1 and 60g of water were mixed with 160g of fly ash to obtain substance B;

[0110] (3) Mix material A, material B, 870g of sand (medium sand), and 784g of crushed stone (320g of 5-10mm crushed stone and 464g of 10-16mm crushed stone) evenly to obtain frost-resistant and crack-resistant modified ballastless track concrete.

[0111] Technical effects:

[0112] 1. Concrete shrinkage reduction effect:

[0113] The shrinkage test results of the concrete obtained in Examples 1-4 are shown in Table 1. The test standard is GB / T50082. The dosage of the antifreeze and anti-cracking agent for ballastless track concrete prepared in this invention is fixed at 0.8% of the cementitious material (cement). The comparative example (Blank) used is concrete without the antifreeze and anti-cracking agent for ballastless track concrete, and the other components remain unchanged.

[0114] Table 1. Results of concrete shrinkage experiments

[0115] Group Dosage % <![CDATA[7d(×10 -6 )]]> <![CDATA[28d(×10 -6 )]]> <![CDATA[60d(×10 -6 )]]> Blank 0 -18.95 -25.19 -36.22 Example 1 0.8 -12.99 -17.96 -28.40 Example 2 0.8 -13.10 -17.85 -27.23 Example 3 0.8 -13.21 -18.04 -27.48 Example 4 0.8 -13.09 -17.62 -26.11

[0116] As can be seen from the concrete shrinkage results in Table 1, the antifreeze and anti-cracking agent for ballastless track concrete prepared in this embodiment of the invention can significantly reduce the shrinkage value of concrete at all ages, and the shrinkage reduction effect is excellent.

[0117] 2. Concrete antifreeze effect:

[0118] The results of the antifreeze test on the concrete obtained in Examples 1-4 are as follows: Figure 1 and Figure 2 As shown, the testing standard is GB / T 50082. The dosage of the antifreeze and anti-cracking agent for ballastless track concrete prepared in this invention is fixed at 0.8% of the amount of cementitious material. The comparative example (Blank) used is concrete without the antifreeze and anti-cracking agent for ballastless track concrete, and the other components remain unchanged.

[0119] from Figure 1 The results show that the mass loss of all four groups of samples incorporating the antifreeze and crack-resistant agent for ballastless track concrete was lower than that of the blank group. Figure 2 As can be seen, the strength loss of the four groups of samples with antifreeze and crack-resistant agent for ballastless track concrete was lower than that of the blank group, indicating that the addition of antifreeze and crack-resistant agent for ballastless track concrete plays a certain protective role for cement-based materials, reduces the impact of freeze-thaw cycles on the structure of cement-based materials, and has excellent antifreeze effect.

[0120] 3. Crack resistance of concrete:

[0121] The crack resistance test results of the concrete obtained in Examples 1-4 are shown in Table 2. The test standard is GB / T50082. The dosage of the antifreeze and anti-cracking agent for ballastless track concrete prepared in this invention is fixed at 0.8% of the amount of cementitious material. The comparative example used is concrete without the addition of antifreeze and anti-cracking agent for ballastless track concrete, and the other components remain unchanged.

[0122] Table 2 Results of concrete crack resistance tests

[0123]

[0124] As can be seen from the concrete crack resistance results in Table 2, the cracking time of each embodiment with added antifreeze and anti-cracking agent for ballastless track concrete is longer than that of the comparative example. The crack width and crack area of ​​each embodiment with added antifreeze and anti-cracking agent for ballastless track concrete are smaller than those of the comparative example, and the crack resistance effect is significantly improved.

[0125] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An antifreeze and crack-resistant agent for ballastless track concrete, characterized in that, The molecular structure is shown below: ； Wherein, R1 is -OH or H; R2 is or ; R3 is or ; The m and n are positive integers, representing the number of repeating units in each part of the polymer. The range of m is 5-20, and the range of n is 500-2000.

2. The method for preparing an antifreeze and crack-resistant agent for ballastless track concrete as described in claim 1, characterized in that, Includes the following steps: After modification, the polyphenolic compound dimer is reacted with amino acids in an aqueous solution to form a Schiff base. The resulting Schiff base reaction product, polyester compound, and catalyst A are then dissolved in a solvent and stirred under nitrogen atmosphere to carry out an acylation reaction. After the reaction is completed, post-treatment is performed to obtain the antifreeze and anti-cracking agent.

3. The method for preparing an antifreeze and crack-resistant agent for ballastless track concrete according to claim 2, characterized in that, The method for modifying polyphenolic compound dimers includes the following steps: Add catalyst B to an aqueous solution of a polyphenol compound and react it at 50-70°C in an oxygen environment for 4-8 hours to obtain a polyphenol compound dimer solution. Mix the polyphenol compound dimer solution, thionyl chloride and catalyst C, and react it under nitrogen conditions for 6-10 hours. Then, after distillation and drying, the modified polyphenol compound dimer is obtained.

4. The method for preparing an antifreeze and crack-resistant agent for ballastless track concrete according to claim 3, characterized in that, The polyphenolic compounds include gallic acid or salicylic acid; and / or The catalyst B comprises potassium permanganate or manganese dioxide; and / or The catalyst C comprises N,N-dimethylformamide and / or dimethyl sulfoxide.

5. A method for preparing an antifreeze and crack-resistant agent for ballastless track concrete according to claim 2, characterized in that, The Schiff base reaction specifically includes the following steps: The pH of the aqueous solution of the modified polyphenolic compound dimer was adjusted to 7-9, and then an aqueous solution of amino acids was added dropwise while stirring under oxygen conditions. After the addition was completed, the reaction was stirred for 2-4 hours. Then the pH was adjusted to 5-7 to obtain the Schiff base reaction product.

6. A method for preparing an antifreeze and crack-resistant agent for ballastless track concrete according to claim 5, characterized in that, The amino acids in the aqueous solution include glutamic acid or aspartic acid.

7. A method for preparing an antifreeze and crack-resistant agent for ballastless track concrete according to claim 2, characterized in that, The polyester compounds include polybutylene succinate or polylactic acid; and / or Catalyst A includes pyridine or dimethyl sulfoxide.

8. The application of the antifreeze and crack-resistant agent for ballastless track concrete as described in claim 1 in concrete.

9. A type of ballastless track concrete, characterized in that, It includes the antifreeze and crack-resistant agent for ballastless track concrete as described in claim 1; the amount of the antifreeze and crack-resistant agent for ballastless track concrete added is 0.8-1% of the cementitious material.

10. A ballastless track concrete according to claim 9, characterized in that, The cementing material is cement.

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